Nearly 1,000 Vietnamese labours returned home after finishing their export labour contracts in South Korea in the first half of 2018, according to a report from the Vietnam Labour Management Board.
The Vietnamese Embassy in South Korea also added that 518 others had been arrested and expelled from the country after overstaying their visas to work illegally.
This year South Korea is expecting to employ 3,500 Vietnamese in manufacturing, excluding the numbers of workers needed for the fishery and agriculture sectors.
Vietnam and South Korea have pledged to work closely on measures to reduce the high rate of illegal workers, with South Korea planning to impose more fines on the companies which employ illegal workers from Vietnam, according to the Department of Overseas Labour Management.
The Vietnamese Department of Overseas Labour have also taken on some measures to encourage people to return home after finishing contracts and temporarily block people from locations with a high number of workers illegally in South Korea.
Last year South Korea recruited 3,600 Vietnamese while also blocked people from dozens of locations in Vietnam to apply to work in the country due to the high rate of illegal workers.
In 2012, South Korea stopped renewing a labour agreement signed with Vietnam in 2004 because the number of Vietnamese workers overstaying their visas to work illegally in South Korea rose to more than 50 percent. Seoul resumed the agreement only in December 2013 after the rate of illegal workers was cut to 38 percent.
Vietnam had sent 40,000 people to work in South Korea by the end of 2016, but South Korea said 39 percent of them had overstayed and been working illegally, the department said.
Vietnamese workers in South Korea receive a minimum wage of more than USD1,000 a month and work 40 hours a week, according to official reports.